Backman H, et al. - The prevalence, incidence and risk factors of chronic airway obstruction (CAO) were determined in a population-based adult asthma cohort. CAO was defined as post-bronchodilator FEV₁/FVC<0.7. CAO development was not seen in the majority of the patients. At study entry, more respiratory symptoms, asthma medication use, and ischemic heart disease were reported by asthmatics with prevalent CAO vs asthmatics without CAO (asthma only). A more rapid FEV₁ decline and higher levels of neutrophils were detected among those who developed CAO during follow-up than asthma only. For prevalent and incident CAO, the identified risk factors included smoking, older age and male sex, these were similar to risk factors described for COPD in the general population.